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This article will take you through the fs file system module and path module in node. I hope it will be helpful to you!
fs module is officially provided by Node.js and is used for operation File module. It provides a series of methods and properties to meet users' file operation needs.
const fs = reuire('fs')
Read the contents of the specified file
1. The syntax format of fs.readFile()
Using the fs.readFile() method, you can read the content in the specified file. The syntax format is as follows:
fs.readFile(path[, options], callback)
2. Sample code of fs.readFile()
Read the contents of the specified file in utf8 format, and print the values of err and data :
const fs = require('fs'); fs.readFile('hello.txt', 'utf-8', (err, data) => { // 判断是否读取成功 if (err) return console.log(err); console.log(data); });
Write content to the specified file
##1. Syntax format of fs.writeFile()
Use the fs.writeFile() method to write content to the specified file. The syntax format is as follows:fs.writeFile(file, data[, options], callback)
2. Sample code for fs.writeFile()
const fs = require('fs'); fs.writeFile('./hello.txt', 'hello node', (err) => { // 判断是否写入成功 if (err) return console.log(err); console.log('写入成功'); });
Read the names of all files in the specified directory
1. The syntax format of fs.readdir()
Using the fs.readdir() method, you can read the names of all files in the specified directory. The syntax format is as follows:fs.readdir(path[, options], callback)
2. Sample code of fs.readdir()
Through the fs.readdir() method, you can read the names of all files in the specified directory :const fs = require('fs'); fs.readdir('./', (err, data) => { // 错误处理 if (err) return console.log(err); console.log(data); });
fs module-path dynamic splicing problem
When using the fs module to operate files, if the provided operation path starts with . When the relative path starts with / or ../, it is easy to cause dynamic path splicing errors. This is because when the code is running, the full path of the file being operated will be dynamically spliced from the directory where the node command is executed. Solution: When using the fs module to operate files, provide absolute paths directly instead of relative paths starting with ./ or ../ to prevent dynamic path splicing problems. Note: Use __dirname to get the absolute path of the current fileconst fs = require('fs'); // 拼接要读取文件的绝对路径 let filepath = __dirname +'/hello.txt' fs.readFile(filepath, 'utf-8', (err, data) => { // 判断是否读取成功 if (err) return console.log(err); console.log(data); });
const path = require('path')
Path splicing
The syntax format of path.join()
Use the path.join() method to combine multiple paths The fragments are spliced into a complete path string. The syntax format is as follows:path.join([...paths])Use the path.join() method to splice multiple path fragments into a complete path string:
const path = require('path'); console.log( path.join('a', 'b', 'c') ); // a/b/c console.log( path.join('a', '/b/', 'c') ); // a/b/c console.log( path.join('a', '/b/', 'c', 'index.html') ); // a/b/c/index.html console.log( path.join('a', 'b', '../c', 'index.html') ); // a/c/index.html console.log(__dirname); // node自带的全局变量,表示当前js文件所在的绝对路径 // 拼接成绩.txt的绝对路径 console.log( path.join(__dirname, '成绩.txt') ); // ------ 最常用的
Get the file name in the path
1. The syntax format of path.basename()
Use path.basename( ) method, you can get the last part of the path. You often use this method to get the file name in the path. The syntax format is as follows:path.basename(path[,ext])
2.path.basename()的代码示例
使用 path.basename() 方法,可以从一个文件路径中,获取到文件的名称部分:
// 找文件名 console.log( path.basename('index.html') ); // index.html console.log( path.basename('a/b/c/index.html') ); // index.html console.log( path.basename('a/b/c/index.html?id=3') ); // index.html?id=3 console.log(path.basename('/api/getbooks')) // getbooks
获取路径中的文件扩展名
1.path.extname()的语法格式
使用 path.extname() 方法,可以获取路径中的扩展名部分,语法格式如下:
path.extname(path)
使用 path.extname() 方法,可以获取路径中的扩展名部分
// 找字符串中,最后一个点及之后的字符 console.log( path.extname('index.html') ); // .html console.log( path.extname('a.b.c.d.html') ); // .html console.log( path.extname('asdfas/asdfa/a.b.c.d.html') ); // .html console.log( path.extname('adf.adsf') ); // .adsf
原文地址:https://juejin.cn/post/7088650568150810638
作者:L同学啦啦啦
更多node相关知识,请访问:nodejs 教程!
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